Ian and Grant,
Congratulations for a very dynamic video, which was well shot and well edited. Pretty legit for graduating high school seniors! :)
May I make a few suggestions if you ever do an updated version or a follow-up?
1) Around the 1 minute mark, when you state the equations for circular motion, it would have been great for them to appear in overlay over the shot of you two talking.
2) Around the 1 minute 20 second mark, you state that when you let go of the string, the ball continues in a straight line, before being affected by gravity and curving toward the edge of the frame... but of course, gravity starts acting right away, so the ball starts to curve at the very instant you let go of the string, but because the curvature is not that pronounced, it takes a while before it becomes clear that the motion is not straight. It would have been more acurate to explain it right away the way you correctly explained it at the end of the video (around the 3 minutes 55 seconds mark): the ball flies off on a TANGENTIAL path and its trajectory is parabolic.
3) Around the 3 minute mark, when you actually do the experiment with sparks, it would have been great to see you spin the apparatus in daylight before going to the night shots: I knew what you were going to do with the apparatus as soon as as I saw you building it, but it may not have been that clear for some viewers.
Congratulations once again: I hope your video does well in this contest. Good luck!
Marc
P.S. Thank your for reviewing (and presumably rating) part 1 of my trilogy of videos "This Is Physics". If you have the time to leave a critique and rate the other two parts using your author code, it would be quite appreciated. I think many of the participants in the contest have not yet realized that a video needs to get AT LEAST 10 COMMUNITY RATINGS to be considered for the final round, so I have started to actively ask for ratings... Don't hesitate to do the same, many authors had to resort to this approach in the previous contests organized by FQXi...
